1. Field of the Invention
The present invention relates generally to a portable, hand held, manually operated, manually powered suction device for capturing small objects such as insects or solder, and more particularly, to a suction pistol or pencil which includes a manually operated pump for producing and storing a vacuum in a chamber of the device.
2. Description of the Prior Art
Many different types of devices have been invented for capturing insects. Since early times, man has been collecting insects for study or for extermination. Rather simple devices have involved nettings or other closures which may be placed over the insect. As time passed, more sophisticated devices were used, such as fly paper and suction devices using a spring-loaded piston. The type of device, and consequently its structure, has depended upon the interest of the user. The entomologist has been interested in capturing the insect alive and studying it. The normal home-user has been interested in catching and exterminating the insects.
In the field of household insect extermination, the use of a hand-held spray from bottles or aerosol cans is common. The use of these sprays can be harmful or dangerous to humans (especially children) and animals and they can stain furniture or other objects.
The popularity of aerosol sprays can be partially attributed to the impersonal act of killing the insect. Many people are more reticent towards using a physical extermination device, such as fly swatter, then they are towards using a relatively impersonal chemical method. An even more impersonal and humane way of disposing of insects would be the use of a suction gun wherein the insect would be sucked into a chamber to be ejected elsewhere, possibly outdoors. Killing of the insect is then optional. The suction gun can be used for capturing an insect for study as well as for disposing of it with or without killing. The latter, of course, would be preferable to the insect and is a goal of this invention.
The use of manually operated suction guns is old in the art. These guns have generally involved a piston pump, spring loaded and released by a trigger to create a suction into the gun or catching device. The major problem with these devices is the pulse shape and weakness of the suction pulse. Due to the mass and inertia of the spring and piston, the suction builds up gradually as the piston accelerates and ends suddenly as the piston reaches the end of its travel. It would be more efficient to begin immediately with maximum suction when the insect is at maximum range and at a most unpredictable velocity relative to the muzzle, and gradually decrease the suction as the insect nears and enters the device. Also, the overall strength of the suction pulse of such devices is limited by the volume displacement of one stroke of the piston. Motor driven devices have strong suction but are complex to construct and operate. Neither manually operated nor motor driven insect suction guns have been found to be accepted.
It is partly to this critical problem of the prior art that the present invention is directed. By initially building a strong vacuum in an integrating chamber as a result of repeated reciprocation of a piston, maintaining it until one is within close vicinity of the insect, and suddenly opening a shutter device to expose the evacuated chamber to the atmosphere, a large and instantaneous suction is created which draws the insect into the catch chamber.
Because only the mass and inertia of air is involved, the maximum suction is reached almost instantaneously and then decreases to zero as the chamber fills with air until its pressure becomes atmospheric. Because of the integrating technique, e.g., check valve means and repeated reciprocation of the piston to repeatedly draw air from a vacuum storage chamber, the vacuum is strong and the strength of the suction pulse is large in comparison to the size of the vacuum storage chamber and the piston pump. By repeated operation of the pump means, energy may thus be stored at high energy density (strong vacuum) in a chamber volume much larger than the volume of the pump means. The pumping action is thus added or integrated over a number of cycles of the pump.
Then by suddenly and completely discharging the stored vacuum instantaneously by means of a rapid acting, wide opening shutter valve (through which a captured object passes), the manually powered, hand held suction device can produce a large suction force in proportion to its size and weight and in proportion to the manual force required to operate the pump. Using the same integrating technique in reverse, the storage chamber can be pressurized with high pressure and then the insect suddenly ejected from the catch chamber and gun.
A number of manually operated, hand held suction type desoldering devices have been invented for removing molten solder from an electrical terminal after the terminal or connection is heated by means of a soldering iron to melt the solder. Such devices generally utilize a spring loaded piston and are used primarily for removing excess solder from an electrical connection or for desoldering an electrical connection in order to remove an electrical component. They also can be used for retrieving small work parts accidentally dropped into an electrical assembly, as well as solidified bits of solder, and are generally small and pencil or cigar shaped for ease of carrying and holding and for operation in confined work spaces.
The spring loaded piston devices utilize energy manually stored in the spring to accelerate the piston in a cylinder upon trigger release of a piston latching means. The piston motion produces a vacuum in the cylinder chamber and an adjoining nozzle at one end of the cylinder chamber as the piston accelerates away from the nozzle, and the resulting action draws the molten solder into the nozzle. The piston has a nipple which is integral with the piston and fits into the nozzle for mechanically ejecting from the nozzle the captured, now solidified, solder in case the pressure resulting from the return of the piston toward the nozzle is insufficient to eject the solder. Because of the inertia of the piston and spring, which limits their rate of acceleration for a given spring force, and because of their limited distance of travel in the cylinder before they must start decelerating, the suction or pressure builds up slowly and is never very strong, the energy stored in the spring being disssipated slowly over a relatively long period of time, as with the prior art insect suction guns. Because the nipple is within and therefore restricts flow through the nozzle during the early part of the suction pulse, a small differential pressure is created across the nozzle during the initial part of the suction stroke and is converted substantially instantaneously into suction when the nipple leaves the nozzle. This increases the suction force and capturing capability somewhat, but this increase is relatively small by virtue of leakage of air through the nozzle around the nipple, as well as by virtue of the small fraction of the suction stroke that the nipple acts as a flow restrictor. Another limitation of this technique is that the acceleration and deceleration of the piston and spring cause a recoil of the device which can be irritating to the operator and even dangerous to the operator or the apparatus, and can move the nozzle away from the electrical connection before the suction pulse is complete, thereby reducing the amount of molten solder that is captured. Another difficulty with the spring loaded piston devices is that solder sometimes passes through the nozzle into the variable volume cylinder chamber and may jam the piston as well as present added difficulty in its removal from the device. The captured solder is sometimes trapped and difficult to remove as a result of the necessarily larger cylinder diameter than the diameter of the nozzle.
Other manually operated manually powered, hand held suction type capturing devices have been invented but these appear generally to be less practical than the devices described above. Some of the devices utilize air flow induced by a moving piston or other operating pump means to eject a captured object, but the pressure developed in this way is very close to atmospheric and thus has limited capability for ejecting from the device a captured object which tends to stick to the walls of the device.